| 1. |
- Axelsson, Magnus A. B., et al.
(författare)
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Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins.
- 2001
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 11:8, s. 633-44
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Tidskriftsartikel (refereegranskat)abstract
- Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.
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| 2. |
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| 3. |
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| 4. |
- Fairweather, J. K., et al.
(författare)
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Structural characterization by C-13-NMR spectroscopy of products synthesized in vitro by polysaccharide synthases using C-13-enriched glycosyl donors : application to a UDP-glucose:(1 -> 3)-beta-D-glucan synthase from blackberry (Rubus fruticosus)
- 2004
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 14:9, s. 775-781
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Tidskriftsartikel (refereegranskat)abstract
- A simple and sensitive method for the characterization of products synthesized in vitro by polysaccharide synthases is described. it relies on the use of C-13-enriched nucleotide sugars as substrates and on the analysis of the newly synthesized polysaccharides by C-13-nuclear magnetic resonance (NMR) spectroscopy. The method was validated with a (1-->3)-beta-D-glucan synthase from blackberry, but it may be applied to the study of any glycosyltransferase. The chemical synthesis of UDP-D-[U-C-13]glucose was achieved in a classical procedure with an overall yield of 50%. A uniformly labeled (1-->3)-beta-D-glucan was synthesized from this substrate, using detergent extracts of blackberry cell membranes as a source of synthase. One hundred micrograms of product was sufficient for liquid and solid-state C-13-NMR spectroscopy analyses. The method is at least 100 times more sensitive than in the case of non-enriched polysaccharides. It allows the unequivocal identification and direct structural characterization of the products synthesized in vitro, as opposed to conventional methods that rely on the use of radioactive substrates and enzymatic hydrolysis of the polysaccharides with specific glycoside hydrolases. The method proves that the glycan analyzed was synthesized de novo because the final product is enriched in C-13. Information on the 3D organization of the polymer may also be obtained by solid-state NMR spectroscopy.
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| 6. |
- Hellström, Ulrika, 2000, et al.
(författare)
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Carbohydrates act as receptors for the periodontitis-associated bacterium Porphyromonas gingivalis: a study of bacterial binding to glycolipids.
- 2004
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 14:6, s. 511-9
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Tidskriftsartikel (refereegranskat)abstract
- In this study we show for the first time the use of carbohydrate chains on glycolipids as receptors for the periodontitis-associated bacterium Porphyromonas gingivalis. Previous studies have shown that this bacterium has the ability to adhere to and invade the epithelial lining of the dental pocket. Which receptor(s) the adhesin of P. gingivalis exploit in the adhesion to epithelial cells has not been shown. Therefore, the binding preferences of this specific bacterium to structures of carbohydrate origin from more than 120 different acid and nonacid glycolipid fractions were studied. The bacteria were labeled externally with (35)S and used in a chromatogram binding assay. To enable detection of carbohydrate receptor structures for P. gingivalis, the bacterium was exposed to a large number of purified total glycolipid fractions from a variety of organs from different species and different histo-blood groups. P. gingivalis showed a preference for fractions of human and pig origin for adhesion. Both nonacid and acid glycolipids were used by the bacterium, and a preference for shorter sugar chains was noticed. Bacterial binding to human acid glycolipid fractions was mainly obtained in the region of the chromatograms where sulfated carbohydrate chains usually are found. However, the binding pattern to nonacid glycolipid fractions suggests a core chain of lactose bound to the ceramide part as a tentative receptor structure. The carbohydrate binding of the bacterium might act as a first step in the bacterial invasion process of the dental pocket epithelium, subsequently leading to damage to periodontal tissue and tooth loss.
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| 7. |
- Hood, D W, et al.
(författare)
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Genetic basis for expression of the major globotetraose-containing lipopolysaccharide from H-influenzae strain Rd (RM118)
- 2001
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 11:11, s. 957-967
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Tidskriftsartikel (refereegranskat)abstract
- A genetic basis for the biosynthetic assembly of the globotetraose containing lipopolysaccharide (LPS) of Haemophilus influenzae strain RM118 (Rd) was determined by structural analysis of LPS derived from mutant strains. We have previously shown that the parent strain RM118 elaborates a population of LPS molecules made up of a series of related glycoforms differing in the degree of oligosaccharide chain extension from the distal heptose residue of a conserved phosphorylated inner-core element, L-alpha -D-Hepp-(1-->2)-L-alpha -D-Hepp-(1-->3)-[beta -D-Glcp-(1-->4)-]-L-alpha -D-Hepp-(1-->5)-alpha -Kdo. The fully extended LPS glycoform expresses the globotetraose structure, beta -D-GalpNAc-(1-->3)-alpha -D-Galp(1-->4)-beta -D-Galp-(1-->4)-beta -D-Glcp. A fingerprinting strategy was employed to establish the structure of LPS from strains mutated in putative glycosyltransferase genes compared to the parent strain. This involved glycose and linkage analysis on intact LPS samples and analysis of O-deacylated LPS samples by electrospray ionization mass spectrometry and 1D H-1-nuclear magnetic resonance spectroscopy. Four genes, lpsA, lic2A, lgtC, and lgtD, were required for sequential addition of the glycoses to the terminal inner-core heptose to give the globotetraose structure. lgtC and lgtD were shown to encode glycosyltransferases by enzymatic assays with synthetic acceptor molecules. This is the first genetic blueprint determined for H. influenzae LPS oligosaccharide biosynthesis, identifying genes Involved in the addition of each glycose residue.
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| 8. |
- Lang, Tiange, 1976, et al.
(författare)
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Bioinformatic identification of polymerizing and transmembrane mucins in the puffer fish Fugu rubripes
- 2004
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 14:6, s. 521-527
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Tidskriftsartikel (refereegranskat)abstract
- Mucins are large glycoproteins characterized by mucin domains that show little sequence conservation and are rich in the amino acids Ser, Thr, and Pro. To effectively predict mucins from genomic and protein sequences obtained from genome projects, we developed a strategy based on the amino acid compositional bias characteristic of the mucin domains. This strategy is combined with an analysis of other features commonly found in mucins. Our method has now been used to predict mucins in the puffer fish Fugu rubripes that were previously not identified or annotated. At least three gel-forming mucins were found with the same general domain structure as the human MUC2 mucin. In addition one transmembrane mucin was identified with SEA and EGF domains as found in the mammalian transmembrane mucins. These results suggest that the number of gel-forming mucins has been conserved during evolution of the vertebrates, whereas the family of transmembrane mucins has been markedly expanded in the higher vertebrates.
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| 9. |
- Li, J J, et al.
(författare)
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Glycine is a common substituent of the inner core in Haemophilus influenzae lipopolysaccharide
- 2001
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 11:12, s. 1009-1015
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Tidskriftsartikel (refereegranskat)abstract
- A survey of both typeable and nontypeable strainsof Haemophilus influenzae indicated that they contain glycine (Gly) in their lipopolysaccharide (LPS). Significant amounts (30-250 pmol Gly/mug LPS) were determined by high-performance anion-exchange chromatography using pulsed amperometric detection after treatment of the LPS with mild alkali. Oligosaccharides obtained from LPS after mild acid hydrolysis and gel filtration chromatography were investigated by electrospray ionization mass spectrometry (ESI-MS) and capillary electrophoresis (CE) ESI-MS. In all cases, molecular ions corresponding to the major glycoforms were identified and were accompanied by ions differing by 57 Da, thus indicating the presence of glycine. The position of glycine in these glycoforms was determined by CE-ESI-MS/MS analyses. It was found that, depending on strain, glycine can substitute each of the heptoses of the inner-core element, L-alpha-D-Hepp-(1-->2)-[PEtn-->6]-L-alpha-D-Hepp-(1-->3)-L-alpha-D-Hepp- (1-->5)-alpha-Kdo of H. influenzae LPS as well as Kdo. In some strains, mixtures of monosubstituted Gly-containing glycoforms having different substitution patterns were identified.
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